TD5 blowing fuses, help wanted.

[guitarcher]

Defender TD5 2006.

Indicator and instrument fuses keep blowing and the headlights go out. Only blew the high beam light fuses once but others keep blowing. When the fuses blow there is no power at the fuse. After removing the steering wheel and pulling off the light/indicator/horn switch power is miraculously restored???

I have fitted a new light/indicator/horn switch and still have the problem.

After replacing the fuses I might get 10 minutes driving before the fuses blow again. Still have dash lights, tail lights and parkers working.

Any help greatly appreciated, thanks.

[mattandersonAU]

It does sound like a problem at the switch. Have you replaced the headlight switch as well? Or just the indicator/horn switch?

[guitarcher]

It does sound like a problem at the switch. Have you replaced the headlight switch as well? Or just the indicator/horn switch?

Thanks for your reply.

Have not replaced the headlight switch yet. It looks ok with no arcing. When the fuses have blown there is always power across the headlight switch terminals but not at the fuses.

I've just replaced the indicator and instrument fuses and now everything is working again,.....for a short time no doubt.

[mattandersonAU]

I'd probably replace the headlight switch first off. When mine went, it worked intermittently and popped a fuse on two occasions.

They have a habit of burning out as the current for the lights is drawn through the switch through bad design.
If you do replace the switch I would recommend also installing the new wiring loom that includes relays so the current bypasses the switch and goes directly to your lights - should be plenty of info on that around the forum. It's not a difficult or expensive job and worked a treat for me. Also made my headlights a fair bit brighter.

[BilboBoggles]

Just curious - When the lights go out are you doing anything - for example does the fuse blow when you turn the lights on?

Are you Hazard lights working? (The Hazard light relay and switch itself can eb a problem)

Were you towing a trailer? (Ie trailer wiring can blow fuses.)

Unfortunately intermittent shorts are a pain the arse to find. I had an issue with blowing fuses for nearly 3 months on my TD5. It turned out to be a rubbing wiring harness on the inner wing near the steering box side of the engine bay. The insulation had rubbed through. But It too miraculously fixed it self when I went to change the fuse.

You might want to visually follow the wiring harnesses from the lights back to the bulkhead and just see if there are any shiny spots. There are a few places on a TD5 that tend to rub - for example the wiring that runs by the servo booster, that's another place that wore through on mine.


The best situation you can get into would be if it permanently shorted out. If that happens then wire a 12v light bulb across the fuse contacts. The bulb will limit the current, and will glow whilst it's shorted out. Then you can hop out and wiggle things until the light goes out.

[guitarcher]

Just curious - When the lights go out are you doing anything - for example does the fuse blow when you turn the lights on?

Are you Hazard lights working? (The Hazard light relay and switch itself can eb a problem)

Were you towing a trailer? (Ie trailer wiring can blow fuses.)

Unfortunately intermittent shorts are a pain the arse to find. I had an issue with blowing fuses for nearly 3 months on my TD5. It turned out to be a rubbing wiring harness on the inner wing near the steering box side of the engine bay. The insulation had rubbed through. But It too miraculously fixed it self when I went to change the fuse.

You might want to visually follow the wiring harnesses from the lights back to the bulkhead and just see if there are any shiny spots. There are a few places on a TD5 that tend to rub - for example the wiring that runs by the servo booster, that's another place that wore through on mine.


The best situation you can get into would be if it permanently shorted out. If that happens then wire a 12v light bulb across the fuse contacts. The bulb will limit the current, and will glow whilst it's shorted out. Then you can hop out and wiggle things until the light goes out.

For clarification, it is the instrument fuse that is blowing, after that the lights will not work even tho the light fuses are ok. The indicator fuse is also blowing but not at the same time as the instrument fuse.

Hazard lights are working as are the tail lights, parker lights and instrument lights.

The instrument and indicator fuses blow whether the headlights are on or not.

When the instrument fuse is replaced the headlights work again.

I can't understand how the instrument fuse is linked with stopping the headlights working.

I have no trailer wiring.

The headlight wiring and relays were upgraded several years ago and all still looks good and is well protected.

Thanks for any further advice.

[wrinklearthur]

I have a wiring diagram for the Defender, but it's over in the shed at the moment, I'll round it up today and have a look at what wires that are common to that fuse.

Do you have a owners handbook for your Defender, I will need from you conformation of the fuse number as per that manual?
.

[CraigE]

You may have trailer wiring regardless of a tow hitch, maybe worth looking at often these can arc. I personally have had this issue and look like having it again with blowing fuses for dash lights, tail lights, but do not lose the head lights. Could also be in the wiring harness where the joins are and this can be a PIA as it is actually inside the rear pass side of the chassis.

[guitarcher]

I have a wiring diagram for the Defender, but it's over in the shed at the moment, I'll round it up today and have a look at what wires that are common to that fuse.

Do you have a owners handbook for your Defender, I will need from you conformation of the fuse number as per that manual?
.

Hi Arthur,

Sorry for the late reply, i have been on night shift.

The instrument fuse is No.15 (5A) , and the indicator fuse is No.21 (10A).

A sparky at work looked over the wiring diagram with me and we think the instruments are linked through the headlight relay, which he checked out to be ok.

When resistance is measured at the indicator fuse the value is 0.7 Ohms which equates to 17 Amps current draw which is a bit too much for a 10A fuse:D

Unfortunately we didn't get any further to finding the cause.

[Tombie]

What headlight relay :angel::eek:

[guitarcher]

What headlight relay :angel::eek:

The one located under the fuses.Third from the right. ???

[Leyland1980]

The one located under the fuses.Third from the right. ???

There famously in no headlight relay in the Defender! hence there tendency to burn out HL switches and the general dimness of the HLs. once you have identified your current (no pun intended) issue then I would recommend fitting one.

[CraigE]

May not be your answer but fit a Traxide headlight upgrade kit that includes relay.
The 2 fuses blowing could be related or may not be.
I found my issue blowing dash light and tail light fuse. The expensive Narva weather proof plug had slop in the pin and receiver. Result of hollow pins moving and wearing, losing contact and then contacting again. Fixed today.
I also had problems similar to yours and found it was a solder join in the wiring harness had come apart and was arcing and also arcing onto another wire after wearing through. The issue with this is these joins are in the harness at the back drivers side of the car where the trailer wiring is (regardless of whether you have a towbar fitted or not). This join section is where the harness enters the chassis and can be difficult to find.
The other scenario is you may have a wire or more than one worn through. Look for any wear in your harness looms.

[guitarcher]

There famously in no headlight relay in the Defender! .

Thanks for pointing this out to me.

[Dervish]

The one located under the fuses.Third from the right. ???

There is actually a "headlight relay", and it is in the position mentioned. All it does though is switch the headlights off when the ignition is turned off. So yes, Defenders do have headlight relays; just ones that only stop you from draining your battery by leaving the lights on rather than anything useful.

First up, what that fuse 15 does; it is powered directly from the ignition switch and feeds a number of things that need to know when the vehicle is switched on. Some examples: A/C, heater, blower, heated screens, headlights, power windows and instruments. In theory, none of those should work without the fuse. The instruments are not linked through that headlight relay. The relay is switched by a feed from that fuse - and the instruments are powered from that fuse - but they are not really related functionally.

Apart from that, I can't really help - not enough information. I would suggest that the problem may be that the two circuits (fuse 21 and fuse 15) are shorting to each other. That is the only suggestion I can offer.

[guitarcher]

There is actually a "headlight relay", and it is in the position mentioned. All it does though is switch the headlights off when the ignition is turned off. So yes, Defenders do have headlight relays; just ones that only stop you from draining your battery by leaving the lights on rather than anything useful.

First up, what that fuse 15 does; it is powered directly from the ignition switch and feeds a number of things that need to know when the vehicle is switched on. Some examples: A/C, heater, blower, heated screens, headlights, power windows and instruments. In theory, none of those should work without the fuse. The instruments are not linked through that headlight relay. The relay is switched by a feed from that fuse - and the instruments are powered from that fuse - but they are not really related functionally.

Apart from that, I can't really help - not enough information. I would suggest that the problem may be that the two circuits (fuse 21 and fuse 15) are shorting to each other. That is the only suggestion I can offer.

Thanks for clearing that up Dervish.

It looks like a trip to the auto electrician coming up.